Apparatus and methods for monitoring and responding to power supply and/or detection circuit failures within an electronic circuit breaker

ABSTRACT

An electronic circuit breaker may include a monitoring circuit configured to monitor and respond to a power supply and/or detection circuit failure within the electronic circuit breaker. In some embodiments, the monitoring circuit may monitor a regulated DC voltage provided by the detection circuit within the electronic circuit breaker. A response to a power supply and/or detection circuit failure may include interrupting current flow between an electrical power source and an electrical circuit protected by the electronic circuit breaker. Methods of monitoring and responding to a power supply and/or detection circuit failure within an electronic circuit breaker are also provided, as are other aspects.

RELATED APPLICATION

This claims the benefit of U.S. Provisional Patent Application No.62/080,481, filed Nov. 17, 2014 and titled “Method And Apparatus ToMonitor Power Supply And IC Or ASIC Failure In Ground Fault Or Arc FaultCircuit Interrupters Or Dual Function Interrupters,” the disclosure ofwhich is hereby incorporated by reference herein in its entirety for allpurposes.

FIELD

The invention relates generally to electronic circuit breakers and, moreparticularly, to monitoring and responding to power supply and/ordetection circuit failures within an electronic circuit breaker.

BACKGROUND

Electronic circuit breakers may be used in some electrical systems toprotect an electrical circuit coupled to an electrical power source fromone or more fault conditions. One type of electronic circuit breaker maybe a ground fault circuit interrupter (GFCI). GFCIs may be used toprevent electrical shock hazards and are typically used in electricalcircuits adjacent to water, such as in bathrooms and/or kitchens.Another type of electronic circuit breaker may be an arc fault circuitinterrupter (AFCI). AFCIs may interrupt power to an electrical circuitwhen an arcing condition within the electrical circuit is detected.GFCIs and AFCIs may also detect other fault conditions such as, e.g.,persistent over current and/or short circuit fault conditions. A thirdtype of electronic circuit breaker may be referred to as a dual functioncircuit breaker, which combines a GFCI and an AFCI. Upon sensing of afault condition, a trip mechanism within the electronic circuit breakermay be activated to interrupt current flow from the electrical powersource to the protected electrical circuit.

An electronic circuit breaker may include an internal power supply thatmay convert a large AC voltage (e.g., 120 VAC) received from anelectrical power source into a low DC voltage. The low DC voltage may beused to power various circuits within the electronic circuit breaker.The various circuits may include integrated circuits (ICs) and/orapplication specific integrated circuits (ASICs) that perform, e.g.,ground fault and/or arc fault detection. However, if a power supply ordetection circuit within the electronic circuit breaker fails (becauseof, e.g., an electrostatic discharge (ESD), a power surge, or a latch-upcondition), the fault detection capability of the electronic circuitbreaker may be compromised. This may result in a dangerous situationwherein a fault condition may occur in an electrical circuit, but theelectrical circuit may remain energized because the electronic circuitbreaker may be unable to detect and respond to the fault condition.

To help avoid such a dangerous situation, some known electronic circuitbreakers may include a manual test feature, wherein a push-to-test (PTT)button, usually located on the face of the device, can be manuallypressed to check that the electronic circuit breaker is operatingproperly. However, because such manual testing may not be performed,other known electronic circuit breakers may employ an automaticself-test or monitoring feature. Such a feature may automatically checkthe functionality of the electronic circuit breaker every two or threehours, for example. But if the internal power supply fails, theautomatic self-test or monitoring feature may also fail, again resultingin a dangerous situation wherein a fault condition may occur, but theelectrical circuit may remain energized.

Accordingly, there is a need for apparatus and methods that monitor andrespond to power supply and/or detection circuit failures within anelectronic circuit breaker.

SUMMARY

According to one aspect, an electronic circuit breaker is provided thatincludes a trip switch configured to open and close a current pathbetween an electrical power source and an electrical circuit; adetection circuit configured to detect and respond to a fault conditionin the electrical circuit, the detection circuit configured to respondto a fault condition by causing the trip switch to open the current pathbetween the electrical power source and the electrical circuit; a powersupply configured to convert an AC voltage received from the electricalpower source into a first DC voltage, the power supply providing thefirst DC voltage to the detection circuit; and a monitoring circuitconfigured to monitor and respond to a power supply or detection circuitfailure within the electronic circuit breaker, wherein the monitoringcircuit is configured to respond to the power supply or detectioncircuit failure by causing the trip switch to open the current pathbetween the electrical power source and the electrical circuit.

According to another aspect, a method of assembling an electroniccircuit breaker configured to monitor and respond to a power supplyand/or a detection circuit failure within the electronic circuit breakeris provided. The method includes electrically coupling a trip switchbetween a source terminal and a load terminal, the trip switchconfigured to open and close a current path in a power conductor betweenthe source terminal and the load terminal; electrically coupling aninput of a power supply to the power conductor, the power supplyconfigured to convert an AC voltage into a first DC voltage andcomprising a first DC voltage output; electrically coupling a detectioncircuit to the first DC voltage output, the detection circuit comprisinga second DC voltage output; and electrically coupling a monitoringcircuit to the power supply input and to the second DC voltage output,wherein the monitoring circuit is configured to respond to a powersupply or detection circuit failure by causing the trip switch to openthe current path between the source terminal and the load terminal.

According to a further aspect, a method of detecting and responding to apower supply and/or a detection circuit failure within an electroniccircuit breaker is provided. The method includes monitoring a DC voltagewithin the electronic circuit breaker, and responding to a drop in theDC voltage below a predetermined voltage level by causing a trip switchto open a current path between a source terminal and a load terminal ofthe electronic circuit breaker.

Still other aspects, features, and advantages of the invention may bereadily apparent from the following detailed description wherein anumber of example embodiments and implementations are described andillustrated, including the best mode contemplated for carrying out theinvention. The invention may also include other and differentembodiments, and its several details may be modified in variousrespects, all without departing from the scope of the invention.Accordingly, the drawings and descriptions are to be regarded asillustrative in nature, and not as restrictive. The invention covers allmodifications, equivalents, and alternatives of the aspects disclosedherein.

BRIEF DESCRIPTION OF DRAWINGS

Persons skilled in the art will understand that the drawings, describedbelow, are for illustrative purposes only. The drawings are notnecessarily drawn to scale and are not intended to limit the scope ofthis disclosure in any way.

FIG. 1A illustrates a schematic circuit diagram of a first electroniccircuit breaker according to embodiments.

FIG. 1B illustrates a schematic circuit diagram of a second electroniccircuit breaker according to embodiments.

FIG. 2 illustrates a schematic circuit diagram of a third electroniccircuit breaker according to embodiments.

FIG. 3 illustrates a flowchart of a method of assembling an electroniccircuit breaker configured to monitor and respond to a power supplyand/or detection circuit failure within the electronic circuit breakeraccording to embodiments.

FIG. 4 illustrates a flowchart of a method of monitoring and respondingto a power supply and/or detection circuit failure within an electroniccircuit breaker according to embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to the example embodiments of thisdisclosure, which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

The aforementioned deficiencies of some electronic circuit breakers maybe overcome by one or more embodiments of the invention. In one aspect,an electronic circuit breaker may include a monitoring circuitconfigured to monitor an operating mode of a power supply and/or adetection circuit within the electronic circuit breaker. The powersupply may provide a DC voltage to power the detection circuit and/orother electronics of the electronic circuit breaker. The monitoringcircuit may be fabricated as an integrated circuit (IC) and, in someembodiments, may monitor an internally regulated DC voltage that isoutput from the detection circuit, which may itself be an IC or anapplication specific integrated circuit (ASIC). Should the power supplyor detection circuit fail, the monitoring circuit may detect the loss ofvoltage at the monitored DC voltage output of the detection circuit andmay respond by activating a trip mechanism of the electronic circuitbreaker. The trip mechanism may be activated in some embodiments byelectrically coupling voltage (e.g., 120 VAC) from an electrical powersource to the gate of an SCR (silicon-controlled rectifier) or TRIAC(triode for alternating current) within the electronic circuit breakerto energize a trip solenoid or electromagnet of the trip mechanism.Activating the trip mechanism may interrupt current flow from theelectrical power source to an electrical circuit protected by theelectronic circuit breaker. The monitoring circuit may thus prevent adangerous situation from occurring wherein a fault condition occurs, butthe electronic circuit breaker may be unable to respond because of apower supply and/or detection circuit failure, which may leave theelectrical circuit dangerously energized.

In other aspects, methods of monitoring and responding to a power supplyand/or detection circuit failure within an electronic circuit breakerare provided, as will be explained in greater detail below in connectionwith FIGS. 1A-4.

FIG. 1A illustrates an electronic circuit breaker 100A in accordancewith one or more embodiments. Electronic circuit breaker 100A may be aground fault circuit interrupter (GFCI) coupled between an AC electricalpower source and an electrical circuit (respectively labeled “SOURCE”and “LOAD” in FIG. 1A). The SOURCE may provide, e.g., 120 VAC, and theLOAD may be an electrical circuit including, e.g., one or moreappliances, lighting fixtures, and/or other electrical equipment. Insome embodiments, the SOURCE may provide other values of AC voltage.

Electronic circuit breaker 100A may include a current transformer 102, atrip mechanism 104, an SCR (silicon-controlled rectifier) 108, and adetection circuit 110 a, which may be fabricated as, or part of, anASIC. Detection circuit 110 a may be configured to detect ground faultsand/or, alternatively or additionally, other types of fault conditions,such as, e.g., arc faults, over currents, and/or short circuits. Currenttransformer 102 may be coupled to a power conductor 112 and a neutralconductor 114. Trip mechanism 104 may include a trip switch 105 and atrip solenoid 106, wherein trip switch 105 may be configured toelectrically couple and decouple AC power from the SOURCE to the LOADvia power conductor 112 (i.e., trip switch 105 may be configured to openand close a current path in power conductor 112 between the SOURCE andthe LOAD). During normal operation (i.e., where no fault conditions aredetected), trip switch 105 may be closed, electrically coupling theSOURCE to the LOAD.

Current transformer 102 may be configured to sense a current imbalancebetween power conductor 112 and neutral conductor 114. A currentimbalance may indicate a fault condition. The sensed current imbalancemay be electrically coupled to detection circuit 110 a, where it may beamplified and compared to a predetermined value at fault circuitry 116.If the current imbalance exceeds the predetermined value, a trip signalmay be output from detection circuit 110 a at a trip pin 118. The tripsignal may be electrically coupled via a resistor 120 to a gate of SCR108, causing SCR 108 to turn on (i.e., to conduct current). In someembodiments, resistor 120 may be about 4.02 k ohms, but mayalternatively have other suitable values. SCR 108 may be a surface mountdevice having a current rating sufficient to energize trip solenoid 106and may have a maximum gate trigger current of 200 uA. In someembodiments, SCR 108 may be, e.g., Part No. S6X8BSRP manufactured byLittlefuse, Inc. of Chicago, Ill. Other suitable SCRs may be usedinstead. When energized by SCR 108, trip solenoid 106 may cause tripswitch 105 to open, electrically disconnecting the SOURCE from the LOAD.

Detection circuit 110 a may include a self-test controller 122configured to monitor a push-to-test (PTT) pin 124. When amanually-operated PTT button 126 is pressed, PTT pin 124 may beelectrically coupled to an electronics ground potential of electroniccircuit breaker 100. In response to self-test controller 122 sensingthat PTT pin 124 is electrically coupled to electronics groundpotential, a signal may be momentarily output at a test pin 128, whichmay be electrically coupled to transistor switch 130 and, in particular,to the base of NPN transistor 131. In some embodiments, transistorswitch 130 may be, e.g., Part No. DTC144EMT2L by Rohm Co., Ltd., ofKyoto, Japan. Other transistor switches suitable for switchingapplications as described herein may be used instead. The signal fromtest pin 128 may cause NPN transistor 131 to turn on (i.e., conductcurrent), which may allow a test current to flow from a DC output pin132 at detection circuit 110 a. A regulated DC voltage, which may beabout +5 VDC in some embodiments, may be provided at DC output pin 132,as described in more detail further below. Other suitable DC voltagesmay alternatively be provided at DC output pin 132. The test current mayflow through a resistor 134 and current transformer 102 via a conductor136, and then through NPN transistor 131 to electronics groundpotential. In some embodiments, resistor 134 may be about 620 ohms,which may set the test current amplitude to about 8 mA. Resistor 134 mayhave other suitable values.

The induced test current may create a current imbalance that may besensed by current transformer 102 and detected by fault circuitry 116 asdescribed above. If fault circuitry 116 successfully detects the inducedtest current imbalance as, e.g., a ground fault, then a trip signal maybe output from detection circuit 110 a at trip pin 118 to cause tripswitch 105 to open as described above. If fault circuitry 116 fails todetect the induced test current imbalance as a fault condition, then notrip signal may be output from detection circuit 110 a at trip pin 118,indicating that the PTT has failed. In response, self-test controller122 may output a signal to an alarm 138 to alert a user (e.g., ahomeowner) that electronic circuit breaker 100A should be replaced.Alarm 138 may provide one or more audible tones and/or visualindications such as, e.g., one or more illuminated warning lamps or LEDs(not shown).

In some embodiments, self-test controller 122 of detection circuit 110 amay also be configured to periodically initiate an automatic self-testof fault circuitry 116 by monitoring a timer 140. As described above fora PTT, a signal may be momentarily output at test pin 128, which iselectrically coupled to the base of NPN transistor 131. The outputtedsignal may cause NPN transistor 131 to turn on, which may allow a testcurrent to flow via conductor 136 from DC output pin 132 throughresistor 134 and current transformer 102, and through transistor switch130 to electronics ground potential. This may create a current imbalancethat may be sensed by current transformer 102 and detected by faultcircuitry 116 as described above. During this time, the trip signaloutput coupled to trip pin 118 from self-test controller 122 may bedisabled so as to not cause trip switch 105 to electrically disconnectthe SOURCE from the LOAD. If the automatic self-test passes the testcriteria, then normal operation of detection circuit 110 a may continue.However, if the automatic self-test fails the test criteria, thenself-test controller 122 may output a signal to alarm 138 as describedabove and/or may output a trip signal at trip pin 118 to trip electroniccircuit breaker 100, electrically disconnecting the SOURCE from theLOAD, as also described above.

Electronic circuit breaker 100A may also include an internal powersupply configured to convert an AC voltage received from the SOURCE intoa DC voltage for use within electronic circuit breaker 100A. The powersupply may include a full wave bridge rectifier 142, a resistor 144, anda capacitor 146. In some embodiments, full wave bridge rectifier 142 maybe, e.g., Part No. LMB10S by Micro Commercial Components Corp., ofChatsworth, Calif. Other suitable full wave bridge rectifiers may beused instead. Full wave bridge rectifier 142 may be electrically coupledat node 143 to receive an AC voltage (which may be, e.g., 120 VAC) fromthe SOURCE. The DC output voltage of full wave bridge rectifier 142 atnode 145 may be electrically coupled via resistor 144 to a supply pin148 of detection circuit 110 a. Detection circuit 110 a may have aninternal shunt regulator 150 a configured to regulate the voltagereceived at supply pin 148 to about +12 VDC in some embodiments.Capacitor 146, which has one terminal electrically coupled to supply pin148 of detection circuit 110 a and the other terminal electricallycoupled to electronics ground potential, may charge quickly throughresistor 144 upon power on of electronic circuit breaker 100A. The valueof resistor 144 may be selected such that capacitor 146 can be chargedto about +12 VDC within a few of milliseconds. The value of capacitor146 may be selected such that enough charge can be held to maintain avoltage on supply pin 148 high enough to keep internal shunt regulator150 a in regulation during the voltage nulls that are output by fullwave bridge rectifier 142. In some embodiments, the value of capacitor146 may be about 3.3 μF and the value of resistor 144 may be about 7.5 kohms. Resistor 144 and/or capacitor 146 may have other suitable values.Internal shunt regulator 150 a may provide in some embodiments aregulated +5 VDC at DC output pin 132 of detection circuit 110 a.

Electronic circuit breaker 100A may be subject to one or more types ofpower supply and/or detection circuit 110 a failures. For example,resistor 144 of the power supply may fail in an open circuit mode, whichmay prevent detection circuit 110 a from being powered. Resistor 144 mayalternatively fail in a short circuit mode, which may cause detectioncircuit 110 a to be damaged by exposure to high voltage. In either powersupply failure mode, detection circuit 110 a may be inoperable, alongwith self-test controller 122. In addition to a power supply failure,detection circuit 110 a and/or one or more other circuits withinelectronic circuit breaker 100A affecting the operation of detectioncircuit 110 a may fail because of damage caused by, e.g., anelectrostatic discharge (ESD), a power surge, or a latch-up condition.Furthermore, the occurrence of a short circuit within electronic circuitbreaker 100A may result in a high current drain on the internallyregulated DC voltage supply that powers some or all of the internalelectronic circuits of electronic circuit breaker 100A. A high currentdrain on shunt regulator 150 a may cause the DC voltage to drop to anunusably low voltage level, such as, e.g., 1 volt or less. Under theseconditions, fault circuitry 116 and/or self-test controller 122 withindetection circuit 110 a may be inoperable. In some known electroniccircuit breakers, each of these types of failures may go undetecteduntil, e.g., a user manually checks the known electronic circuit breakervia a PTT described above. Accordingly, a dangerous situation may existwith known electronic circuit breakers wherein a fault conditionoccurring within an electrical circuit intended to be protected by aknown electronic circuit breaker may not be detected, leaving theelectrical circuit dangerously energized.

Electronic circuit breaker 100A may remedy such a potentially dangeroussituation by including a monitoring circuit 152 configured to monitorand respond to a power supply and/or detection circuit failure withinelectronic circuit breaker 100A In particular, monitoring circuit 152may be configured to monitor a regulated DC voltage within electroniccircuit breaker 100A. More particularly, in some embodiments, monitoringcircuit 152 may be configured to monitor the regulated DC voltage at DCoutput pin 132 of detection circuit 110 a. In other embodiments, aregulated DC voltage may be monitored at other suitable circuit nodes,terminals, or pins within electronic circuit breaker 100A

Monitoring circuit 152 may include a diode 154, resistors 156, 158, and160, a capacitor 162, and a transistor switch 164 electrically coupledas shown in FIG. 1A. That is, the SOURCE (which may provide, e.g., 120VAC) may be electrically coupled to the gate of SCR 108 via diode 154and resistors 156, 158, and 160. In particular, the SOURCE may beelectrically coupled to the anode of diode 154, and the cathode of diode154 may be electrically coupled to one terminal of resistor 156. Diode154 may be used to prevent any large reverse voltages from electricallycoupling to, and likely damaging, monitoring circuit 152 and possiblyother circuits electrically coupled thereto. The other terminal ofresistor 156 may be electrically coupled to one terminal of resistor158, while the other terminal of resistor 158 may be electricallycoupled to one terminal of resistor 160. The other terminal of resistor160 may be electrically coupled to the gate of SCR 108. Capacitor 162,described in more detail further below, may have one terminalelectrically coupled to a node 157 that electrically couples resistor156 to resistor 158, and the other terminal electrically coupled toelectronics ground potential. A collector of an NPN transistor 165 oftransistor switch 164 may be electrically coupled to a node 159 at whichresistor 158 may be coupled to resistor 160. An emitter of NPNtransistor 165 may be electrically coupled to electronics groundpotential.

Transistor switch 164 may also include a resistor divider networkelectrically coupled to the base of NPN transistor 165. The resistordivider network may include resistors 166 and 167. Resistor 166 mayelectrically couple the base of NPN transistor 165 to an external pin168 of transistor switch 164, and resistor 167 may form the resistordivider by electrically coupling the base of NPN transistor 165 to theemitter of NPN transistor 165. In this embodiment, the value of resistor166 may equal the value of resistor 167, which may each be, e.g., about47 k ohms. This may result in a turn-on voltage of NPN transistor 165 ofabout 1.4 volts. The turn on voltage may be adjusted by selectingdifferent values of resistor 166 and resistor 167. External pin 168 oftransistor switch 164 may be electrically coupled to DC output pin 132of detection circuit 110 a. In some embodiments, transistor switch 164may be, e.g., Part No. DTC144EMT2L by Rohm Co., Ltd., of Kyoto, Japan.Other transistor switches suitable for switching applications asdescribed herein may be used instead.

In other embodiments, monitoring circuit 152 may alternatively oradditionally include other suitable circuit components configured tomonitor and respond to power supply and/or detection circuit failureswithin electronic circuit breaker 100A as described herein.

When the power supply (full wave bridge rectifier 142, resistor 144, andcapacitor 146) and detection circuit 110 a of electronic circuit breaker100A are functioning normally, the internally regulated DC voltage at DCoutput pin 132 may be, e.g., about +5 VDC. Other suitable regulated DCvoltages may be output at DC output pin 132. With external pin 168electrically coupled to DC output pin 132, NPN transistor 165 may be on(i.e., conducting current from its collector to its emitter through alow on-resistance path). While NPN transistor 165 is on, the SOURCE maybe electrically coupled to electronics ground potential via diode 154,resistor 156, resistor 158, and NPN transistor 165. This may prevent anelectrical signal from the SOURCE electrically coupling to the gate ofSCR 108 during normal operation, which may prevent SCR 108 from turningon (i.e., conducting) and causing trip switch 105 to open, which woulddisconnect the SOURCE from the LOAD. A purpose of resistor 160 may be toprevent the gate of SCR 108 from being electrically coupled directly toelectronics ground potential. By preventing such a direct electricalcoupling, a trip signal from trip pin 118 of detection circuit 110 a maybe allowed to turn on SCR 108 during normal operation so electroniccircuit breaker 100A may trip as described above when either a faultcondition in the LOAD is detected, a successful PTT button press is madeor, in some embodiments, a failed automatic self-test occurs.

Capacitor 162 may be used to delay a power signal from the SOURCE fromelectrically coupling to the gate of SCR 108 in order to allow theinternally regulated DC voltage electrically coupled to the base of NPNtransistor 165 to first rise to the turn-on voltage of NPN transistor165. This may be required to ensure that a power signal from the SOURCEis electrically coupled to electronics ground potential when electroniccircuit breaker 100A is powering on during normal operation, and not tothe gate of SCR 108, which would prematurely trip electronic circuitbreaker 100A. In some embodiments, capacitor 162 may be about 0.47 μF,but may have other suitable values.

Should resistor 144 fail or should detection circuit 110 a becomedamaged resulting in electronic circuit breaker 100A being inoperable asdescribed above, the internally regulated DC voltage at DC output pin132 may drop below a predetermined voltage level, such as, e.g., 1 volt.This may cause NPN transistor 165 to turn off, which in turn mayelectrically couple the SOURCE (providing, e.g., about 120 VAC) to thegate of SCR 108 through diode 154, resistor 156, resistor 158, andresistor 160. The values of these resistors may be selected to allowenough current (e.g., >200 uA) into the gate of SCR 108 to trigger SCR108 to turn on and thus energize trip solenoid 106, opening trip switch105 as described above. A dangerous situation may thus be avoided. Insome embodiments, resistor 156 may be about 150 k ohms, resistor 158 maybe about 10 k ohms, and resistor 160 may be about 10 k ohms. Othersuitable values may be used in other embodiments.

Electronic circuit breaker 100A may further include, as shown in FIG.1A, a varistor 170, capacitors 171 and 172, and resistor 173. In someembodiments, varistor 170 may be, e.g., Part No. ERZV11A331 by PanasonicCorporation of North America, capacitor 171 may be about 1000 pF,capacitor 172 may be about 0.1 μF, and resistor 173 may be about 4.02 kohms. Other suitable varistors and/or values for capacitors 171 and 172and resistor 173 may be used.

FIG. 1B illustrates an electronic circuit breaker 100B in accordancewith one or more embodiments. Electronic circuit breaker 100B may beidentical or substantially similar to electronic circuit breaker 100A ofFIG. 1A except as herein described. Unlike detection circuit 110 a ofelectronic circuit breaker 100A, detection circuit 110 b of electroniccircuit breaker 100B may not have a DC output pin, such as DC output pin132 of detection circuit 110 a, coupled to a shunt regulator 150 b.Monitoring circuit 152 of electronic circuit breaker 100B may thereforeinstead monitor an alternative output or pin with a DC bias or knownsignal. As shown in FIG. 1B, external pin 168 of transistor switch 164may be alternatively electrically coupled to a pin 133 of detectioncircuit 110 b, which may have a DC bias. Pin 133 may be coupled to faultcircuitry 116 as shown.

When the power supply (full wave bridge rectifier 142, resistor 144, andcapacitor 146) and detection circuit 110 b of electronic circuit breaker100B are functioning normally, the DC bias voltage at pin 133 may beabout +2 VDC. Other suitable values of DC bias voltage may alternativelybe at pin 133. With external pin 168 electrically coupled to pin 133having a DC bias voltage of about +2 VDC, NPN transistor 165, asdiscussed above, may be on (i.e., conducting current from its collectorto its emitter through a low on-resistance path). While NPN transistor165 is on, the SOURCE may be electrically coupled to electronics groundpotential via diode 154, resistor 156, resistor 158, and NPN transistor165. This may prevent an electrical signal from the SOURCE electricallycoupling to the gate of SCR 108 during normal operation, which mayprevent SCR 108 from turning on (i.e., conducting) and causing tripswitch 105 to open, which would disconnect the SOURCE from the LOAD.

Should resistor 144 fail or should detection circuit 110 b becomedamaged resulting in electronic circuit breaker 100B being inoperable asdescribed above, the internally regulated DC voltage may drop below apredetermined voltage level, such as, e.g., 1 volt, and thus also the DCbias voltage at pin 133. This may cause NPN transistor 165 to turn off,which in turn may electrically couple the SOURCE (providing, e.g., about120 VAC) to the gate of SCR 108 through diode 154, resistor 156,resistor 158, and resistor 160 which, as described above, may triggerSCR 108 to turn on and thus energize trip solenoid 106, causing tripswitch 105 to open. A dangerous situation may thus again be avoided.

FIG. 2 illustrates an electronic circuit breaker 200 in accordance withone or more embodiments. Electronic circuit breaker 200 may be a groundfault circuit interrupter (GFCI) coupled between an AC electrical powersource and an electrical circuit (respectively labeled “SOURCE” and“LOAD” in FIG. 2). The SOURCE may provide, e.g., 120 VAC, and the LOADmay be an electrical circuit including, e.g., one or more appliances,lighting fixtures, and/or other electrical equipment. In someembodiments, the SOURCE may provide other values of AC voltage.

Electronic circuit breaker 200 may include a current transformer 202, atrip mechanism 204, a TRIAC 208, a transistor switch 230, and adetection circuit 210, which may be fabricated as, or part of, an ASIC.Detection circuit 210 may be configured to detect ground faults and/or,alternatively or additionally, other types of fault conditions, such as,e.g., arc faults, over currents, and/or short circuits. Currenttransformer 202 may be coupled to a power conductor 212 and a neutralconductor 214. Trip mechanism 204 may include a trip switch 205 and atrip solenoid 206, wherein trip switch 205 may be configured toelectrically couple and decouple AC power from the SOURCE to the LOADvia power conductor 212 (i.e., trip switch 205 may be configured to openand close a current path in power conductor 112 between the SOURCE andthe LOAD). During normal operation (i.e., where no fault conditions aredetected), trip switch 205 may be closed, electrically coupling theSOURCE to the LOAD.

Except as otherwise described below, current transformer 202, tripmechanism 204, transistor switch 230, and detection circuit 210 mayoperate identically or substantially similarly as current transformer102, trip mechanism 104, transistor switch 130, and detection circuit110 a, respectively. In particular, fault circuitry 216, trip pin 218,resistors 220 and 234, test pin 228, NPN transistor 231, conductor 236,alarm 238, timer 240, supply pin 248, and DC voltage regulator 250 mayeach operate and/or function identically or substantially similarly asfault circuitry 116, trip pin 118, resistors 120 and 134, test pin 128,NPN transistor 131, conductor 136, alarm 138, timer 140, supply pin 148,and shunt regulator 150 a, respectively. Note that self-test controller222, PTT pin 224, and PTT button 226 may operate and/or functionidentically or substantially similarly as self-test controller 122, PTTpin 124, and PTT button 126 except that pressing manually-operated PTTbutton 226 may electrically couple PTT pin 224 to +5 VDC (instead ofelectronics ground potential as in electronic circuit breaker 100A) towhich self-test controller 222 may respond by momentarily outputting asignal at test pin 228.

Electronic circuit breaker 200 may include an AC/DC switching powersupply 274 that may be configured to convert an AC voltage (e.g., 120VAC) received from the SOURCE to about +5 VDC. AC/DC switching powersupply 274 may perform half-wave rectification and may include diode275, power supply ASIC 276, and supporting electrical componentsincluding resistors 277, 283, 284, and 288; inductors 278 and 286;capacitors 279, 280, 282, 285, and 287; and diodes 281 and 289. Powersupply ASIC 276 may be, e.g., Part No. LNK562DN-TL by PowerIntegrations, Inc. of San Jose, Calif. Other suitable AC/DC power supplyASICs may be alternatively used.

TRIAC 208 may be used in electronic circuit breaker 200 to energize tripsolenoid 206 on either the positive or negative half cycle in order tomeet a trip time requirement of about 25 mS when electronic circuitbreaker 200 is powered with a 500-ohm ground fault occurring on theLOAD. In comparison with electronic circuit breaker 100A of FIG. 1A,where the power supply is full wave rectified instead of half-waverectified, electronic circuit breaker 200 includes TRIAC 208 instead ofSCR 108 to energize trip solenoid 206 within a prescribed trip timerequirement. TRIAC 208 may be, e.g., Part No. Z0103NA2AL2 by STMicroelectronics, of Geneva, Switzerland. Other suitable TRIACs may beused instead.

In some embodiments, a “snubber” circuit including a resistor 207 and acapacitor 209 may be required to prevent TRIAC 208 from turning onprematurely in the presence of high voltage transients on the AC voltagereceived from the SOURCE. As shown in FIG. 2, one terminal of TRIAC 208may be electrically coupled to one terminal of resistor 207, while theother terminal of resistor 207 may be electrically coupled to oneterminal of capacitor 209. The other terminal of capacitor 209 may beelectrically coupled to the other terminal of TRIAC 208, forming thesnubber circuit.

TRIAC 208 may have a much higher gate trigger current than SCR 108 ofelectronic circuit breaker 100A. In some embodiments, TRIAC 208 may havea gate trigger current of about 3 mA. Compared to the 200 uA gatetrigger current of SCR 108, much more current may be required toelectrically couple the SOURCE to the gate of TRIAC 208 in order toenergize trip solenoid 206. Accordingly, much more current may need tobe shunted to electronics ground during normal operation wherein TRIAC208 is off (i.e., non-conductive).

To accommodate the increased current requirements of TRIAC 208 and alsoremedy a potentially dangerous situation caused by a failure in AC/DCswitching power supply 274 and/or detection circuit 210, electroniccircuit breaker 200 may include a monitoring circuit 252. Monitoringcircuit 252 may be configured to monitor and respond to a power supplyand/or detection circuit failure within electronic circuit breaker 200.In particular, monitoring circuit 252 may be configured to monitor aregulated DC voltage within electronic circuit breaker 200. Moreparticularly, in some embodiments, monitoring circuit 252 may beconfigured to monitor the regulated DC voltage at a DC output pin 232 ofdetection circuit 210. In other embodiments, a regulated DC voltage maybe monitored at other suitable circuit nodes, terminals, or pins withinelectronic circuit breaker 200.

Monitoring circuit 252 may include a diode 254, resistors 256 and 258,an N-channel MOSFET (metal oxide semiconductor field effect transistor)260, capacitors 262 and 263, and a transistor switch 264 electricallycoupled as shown in FIG. 2. That is, the SOURCE (which may provide,e.g., 120 VAC) may be electrically coupled to the gate of TRIAC 208 viadiode 254, resistor 256, and MOSFET 260. In particular, the SOURCE maybe electrically coupled to the anode of diode 254, and the cathode ofdiode 254 may be electrically coupled to one terminal of resistor 256.Diode 254 may be used to prevent any large reverse voltages fromelectrically coupling to, and likely damaging, monitoring circuit 252and possibly other circuits electrically coupled thereto. The otherterminal of resistor 256 may be electrically coupled to a drain ofMOSFET 260, which may also be electrically coupled to one terminal ofcapacitor 262. The other terminal of capacitor 262 may be electricallycoupled to an electronics ground potential of electronic circuit breaker200. Capacitor 262 may filter high voltage transients to prevent damageto MOSFET 260. In some embodiments, capacitor 262 may be about 0.01 μF,but may have other suitable values. Capacitor 263, described in moredetail further below, may have one terminal electrically coupled to agate of MOSFET 260 and the other terminal electrically coupled toelectronics ground potential. A source of MOSFET 260 may be electricallycoupled to the gate of TRIAC 208. The drain of MOSFET 260 may further beelectrically coupled to one terminal of resistor 258. MOSFET 260 mayhave a turn-on voltage Vgs ranging from 3 volts to 4.5 volts and may be,e.g., Part No. BSS127S-7 by Diodes Incorporated, of Plano, Tex. Othersuitable N-channel MOSFETS may be used instead. The other terminal ofresistor 258 may be electrically coupled to the gate of MOSFET 260 andto a collector of an NPN transistor 265 of transistor switch 264. Anemitter of NPN transistor 265 may be electrically coupled to electronicsground potential.

Transistor switch 264 may also include a resistor divider networkelectrically coupled to the base of NPN transistor 265. The resistordivider network may include resistors 266 and 267. Resistor 266 mayelectrically couple the base of NPN transistor 265 to an external pin268 of transistor switch 264, and resistor 267 may form the resistordivider by electrically coupling the base of NPN transistor 265 to theemitter of NPN transistor 265. In this embodiment, the value of resistor266 may equal the value of resistor 267, which may each be, e.g., about47 k ohms. This may result in a turn-on voltage of NPN transistor 265 ofabout 1.4 volts. The turn on voltage may be adjusted by selectingdifferent values of resistor 266 and resistor 267. External pin 268 oftransistor switch 264 may be electrically coupled to DC output pin 232of detection circuit 210. In some embodiments, transistor switch 264 maybe, e.g., Part No. DTC144EMT2L by Rohm Co., Ltd., of Kyoto, Japan. Othertransistor switches suitable for switching applications as describedherein may be used instead.

In other embodiments, monitoring circuit 252 may alternatively oradditionally include other suitable circuit components configured tomonitor and respond to power supply and/or detection circuit failureswithin electronic circuit breaker 200 as described herein.

When AC/DC switching power supply 274 and detection circuit 210 ofelectronic circuit breaker 200 are functioning normally, the internallyregulated DC voltage at DC output pin 232 may be, e.g., about +3.3 VDC.Other suitable regulated DC voltages may be output at DC output pin 232.With external pin 268 electrically coupled to DC output pin 232, NPNtransistor 265 may be on (i.e., conducting current from its collector toits emitter through a low on-resistance path). While NPN transistor 265is on, the gate of MOSFET 260 may be electrically coupled to electronicsground potential, thus turning off MOSFET 260 and preventing anyelectrical signal from the SOURCE electrically coupling to the gate ofTRIAC 208 during normal operation. This may prevent TRIAC 208 fromturning on (i.e., conducting), energizing trip solenoid 206, and causingtrip switch 205 to open, which would disconnect the SOURCE from theLOAD.

Capacitor 263 may be used to delay a power signal from the SOURCE fromelectrically coupling to the gate of MOSFET 260 in order to allow theinternally regulated DC voltage electrically coupled to the base of NPNtransistor 265 to first rise to the turn-on voltage of NPN transistor265. This may be required to ensure that MOSFET 260 stays off,preventing power from the SOURCE from electrically coupling to the gateof TRIAC 208 when electronic circuit breaker 200 is powering on duringnormal operation, which would prematurely trip electronic circuitbreaker 200. In some embodiments, capacitor 263 may be about 0.47 μF,but may have other suitable values.

Should any one of more of diode 275, resistor 277, power supply ASIC276, or any critical components around power supply ASIC 276 fail thatwould cause AC/DC switching power supply 274 to be inoperable, or shoulddetection circuit 210 become damaged internally resulting in detectioncircuit 210 becoming inoperable as described above in connection withelectronic circuit breaker 100A, the internally regulated DC voltage atDC output pin 232 may drop below a predetermined voltage level, such as,e.g., 1 volt. This may cause NPN transistor 265 to turn off, which maycause MOSFET 260 to turn on and electrically couple the SOURCE(providing, e.g., about 120 VAC) to the gate of TRIAC 208 through diode254, resistor 256, and MOSFET 260. The value of resistor 256 may beselected to allow enough current (>3 mA) into the gate of TRIAC 208 totrigger TRIAC 208 to turn on and thus energize trip solenoid 206,opening trip switch 205. A dangerous situation may thus be avoided. Insome embodiments, resistor 256 may be about 10 k ohms and resistor 258may be about 402 k ohms. Other suitable values may be used in otherembodiments.

Electronic circuit breaker 200 may further include, as shown in FIG. 2,a varistor 270, capacitors 271 and 272, and resistor 273. In someembodiments, varistor 270 may be, e.g., Part No. ERZV11A331 by PanasonicCorporation of North America, capacitor 271 may be about 1000 pF,capacitor 272 may be about 0.1 μF, and resistor 273 may be about 4.02 kohms. Other suitable varistors and/or values for capacitors 271 and 272and resistor 273 may be used.

FIG. 3 illustrates a flowchart of a method 300 of assembling anelectronic circuit breaker configured to monitor and respond to a powersupply and/or detection circuit failure within the electronic circuitbreaker in accordance with one or more embodiments. Method 300 mayinclude at process block 302 electrically coupling a trip switch betweena source terminal and a load terminal of the electronic circuit breaker,wherein the trip switch is configured to open and close a current pathin a power conductor between the source terminal and the load terminal.For example, as shown in FIG. 1A, electronic circuit breaker 100A mayhave trip switch 105 electrically coupled between a source terminal 111and a load terminal 113, wherein trip switch 105 may be configured toopen and close a current path in power conductor 112 between sourceterminal 111 and load terminal 113. Similarly, as shown in FIG. 2,electronic circuit breaker 200 may have trip switch 205 electricallycoupled between a source terminal 211 and a load terminal 213, whereintrip switch 205 may be configured to open and close a current path inpower conductor 212 between source terminal 211 and load terminal 213.

At process block 304, method 300 may include electrically coupling aninput of a power supply to the power conductor, wherein the power supplyis configured to convert an AC voltage into a first DC voltage andcomprises a first DC voltage output. In some embodiments, as shown inFIG. 1A, the power supply comprising full wave bridge rectifier 142,resistor 144, and capacitor 146 may have an input at node 143electrically coupled to power conductor 112 (via trip solenoid 106) anda first DC voltage output at node 147. Similarly, as shown in FIG. 2,AC/DC switching power supply 274 may have an input at input pin 243electrically coupled to power conductor 212 and a first DC voltageoutput at output pin 247.

At process block 306, method 300 may include electrically coupling adetection circuit to the first DC voltage output, wherein the detectioncircuit comprises a second DC voltage output. The detection circuit maybe, e.g., detection circuit 110 a of electronic circuit breaker 100A,detection circuit 110 b of electronic circuit breaker 100B, or detectioncircuit 210 of electronic circuit breaker 200. As shown in FIG. 1A,supply pin 148 of detection circuit 110 a may be electrically coupled tonode 147 (i.e., the first DC voltage output) of the power supply ofelectronic circuit breaker 100A and, as shown in FIG. 2, supply pin 248of detection circuit 210 may be electrically coupled to output pin 247(i.e., the first DC voltage output) of AC/DC switching power supply 274.Detection circuit 110 a may have a second DC voltage output at DC outputpin 132, detection circuit 110 b may have a second DC voltage output atpin 133, and detection circuit 210 may have a second DC voltage outputat DC output pin 232. Alternatively, any suitable detection circuitcapable of detecting one or more of the fault conditions described aboveand having a suitable DC voltage output may be used.

At process block 308, method 300 may include electrically coupling amonitoring circuit to the power supply input and to the second DCvoltage output, wherein the monitoring circuit is configured to respondto a power supply or detection circuit failure by causing the tripswitch to open the current path between the source terminal and the loadterminal. The monitoring circuit may be, e.g., monitoring circuit 152 ofelectronic circuit breaker 100A or 100B or monitoring circuit 252 ofelectronic circuit breaker 200. As shown in FIG. 1A, the anode of diode154 of monitoring circuit 152 may be electrically coupled to node 143(i.e., the power supply input) and external pin 168 of transistor switch164 of monitoring circuit 152 may be electrically coupled to DC outputpin 132 of detection circuit 110 a (i.e., the second DC voltage output).Alternatively, as shown in FIG. 1B, external pin 168 of transistorswitch 164 of monitoring circuit 152 may be electrically coupled to pin133 of detection circuit 110 b (i.e., the second DC voltage output). Andas shown in FIG. 2, the anode of diode 254 of monitoring circuit 252 maybe electrically coupled to input pin 243 of AC/DC switching power supply274 and external pin 268 of transistor switch 264 of monitoring circuit252 may be electrically coupled to DC output pin 232 of detectioncircuit 210 (i.e., the second DC voltage output).

In some embodiments, the electrical coupling of a monitoring circuit mayinclude electrically coupling a first pin of the monitoring circuit tothe power supply input, electrically coupling a second pin of themonitoring circuit to the second DC voltage output of the detectioncircuit, and electrically coupling a third pin of the monitoring circuitto a control circuit configured to control the opening (and in someembodiments the closing) of the trip switch (e.g., trip switch 105and/or 205). For example, in those embodiments wherein monitoringcircuit 152 may be fabricated as an IC, a first pin 153 of monitoringcircuit 152 may be electrically coupled to node 143 of electroniccircuit breaker 100A or 100B, external pin 168 of transistor switch 164of monitoring circuit 152 may serve as a second pin of monitoringcircuit 152 and may be electrically coupled to DC output pin 132 or pin133, and a third pin 161 of monitoring circuit 152 may be electricallycoupled to a control circuit comprising SCR 108, capacitors 171 and 172and resistor 173. Similarly, in some embodiments, monitoring circuit 252may be fabricated as an IC wherein a first pin 253 of monitoring circuit252 may be electrically coupled to input pin 243 of AC/DC switchingpower supply 274, external pin 268 of transistor switch 264 ofmonitoring circuit 252 may serve as a second pin of monitoring circuit252 and may be electrically coupled to DC output pin 232, and a thirdpin 261 of monitoring circuit 252 may be electrically coupled to acontrol circuit comprising TRIAC 208, capacitors 271 and 272 andresistor 273.

Note that the above process blocks of method 300 may be executed orperformed in an order or sequence not limited to the order and sequenceshown and described. For example, in some embodiments, process block 302may be performed after or in parallel with process block 304 and/orprocess block 306.

FIG. 4 illustrates a flowchart of a method 400 of detecting andresponding to a power supply and/or a detection circuit failure withinan electronic circuit breaker in accordance with one or moreembodiments. Method 400 may include at process block 402 monitoring a DCvoltage within an electronic circuit breaker. For example, in someembodiments, monitoring circuit 152 may be used to monitor the DCvoltage provided at DC output pin 132 of detection circuit 110 a inelectronic circuit breaker 100A or the DC voltage provided at pin 133 ofdetection circuit 110 b in electronic circuit breaker 100B. In otherembodiments, monitoring circuit 252 may be used to monitor the DCvoltage provided at DC output pin 232 of detection circuit 210 inelectronic circuit breaker 200. Alternatively, monitoring circuit 152and/or monitoring circuit 252 may be used to monitor a DC voltageprovided at another suitable circuit node, terminal, or pin within anelectronic circuit breaker.

At process block 404, method 400 may include responding to a drop in theDC voltage below a predetermined voltage level by causing a trip switchto open a current path between a source terminal and a load terminal ofthe electronic circuit breaker. As described above in connection withelectronic circuit breaker 100A, e.g., the predetermined voltage levelmay be 1 volt or less in some embodiments. Should the DC voltage at DCoutput pin 132 drop to 1 volt or less, monitoring circuit 152 mayrespond by causing trip switch 105 to open the current path in powerconductor 112 between source terminal 111 and load terminal 113 ofelectronic circuit breaker 100A, as shown in FIG. 1A.

More particularly, in some embodiments, a drop in DC voltage at DCoutput pin 132 to 1 volt or less may cause NPN transistor 165 to turnoff, which may divert a current via diode 154 and resistors 156, 158,and 160, as described above, to a control circuit. The control circuitmay include SCR 108, capacitors 171 and 172, and resistor 173. Thecurrent diverted to SCR 108 may cause SCR 108 to turn on, which mayenergize trip solenoid 106 (or, alternatively, an electromagnet). Anenergized trip solenoid 106 may cause trip switch 105 to open, whichopens the current path between source terminal 111 and load terminal 113of electronic circuit breaker 100A. Note that while the DC voltageremains above the predetermined voltage level at DC output pin 132, NPNtransistor 165 may remain on, which may shunt a current to electronicsground potential that would otherwise be diverted to SCR 108.

Persons skilled in the art should readily appreciate that the inventiondescribed herein is susceptible of broad utility and application. Manyembodiments and adaptations of the invention other than those describedherein, as well as many variations, modifications, and equivalentarrangements, will be apparent from, or reasonably suggested by, theinvention and the foregoing description thereof, without departing fromthe substance or scope of the invention. For example, although describedin connection with monitoring a DC voltage in an electronic circuitbreaker, the monitoring circuits and methods described herein may haveapplication in other electronic devices wherein an internal power supplyfailure may be mitigated to avoid undesirable or possibly dangerousconsequences. Accordingly, while the invention has been described hereinin detail in relation to specific embodiments, it should be understoodthat this disclosure is only illustrative and presents examples of theinvention and is made merely for purposes of providing a full andenabling disclosure of the invention. This disclosure is not intended tolimit the invention to the particular apparatus, devices, assemblies,systems or methods disclosed, but, to the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe scope of the invention, as defined by the following claims.

What is claimed is:
 1. An electronic circuit breaker, comprising: a tripswitch configured to open and close a current path between an electricalpower source and an electrical circuit; a detection circuit configuredto detect and respond to a fault condition in the electrical circuit,the detection circuit configured to respond to a fault condition bycausing the trip switch to open the current path between the electricalpower source and the electrical circuit; a power supply configured toconvert an AC voltage received from the electrical power source into afirst DC voltage, the power supply providing the first DC voltage to thedetection circuit; and a monitoring circuit configured to monitor andrespond to a power supply or detection circuit failure within theelectronic circuit breaker, wherein the monitoring circuit is configuredto respond to the power supply or detection circuit failure by causingthe trip switch to open the current path between the electrical powersource and the electrical circuit.
 2. The electronic circuit breaker ofclaim 1, wherein the monitoring circuit is configured to monitor thefirst DC voltage or a second DC voltage derived from the first DCvoltage within the electronic circuit breaker.
 3. The electronic circuitbreaker of claim 1, wherein the monitoring circuit is configured tomonitor the first DC voltage or a second DC voltage derived from thefirst DC voltage, the second DC voltage provided at an output of thedetection circuit.
 4. The electronic circuit breaker of claim 1, whereinthe monitoring circuit is configured to monitor the first DC voltage ora second DC voltage derived from the first DC voltage and to respond toa drop in the first or second DC voltage below a predetermined voltagelevel by causing the trip switch to open the current path between theelectrical power source and the electrical circuit.
 5. The electroniccircuit breaker of claim 1 wherein the monitoring circuit comprises: afirst pin electrically coupled to receive an AC voltage from theelectrical power source; a second pin electrically coupled to receivethe first DC voltage or a second DC voltage derived from the first DCvoltage; and a third pin electrically coupled to a control circuit tocause the trip switch to open the current path between the electricalpower source and the electrical circuit.
 6. The electronic circuitbreaker of claim 1, wherein the monitoring circuit comprises atransistor configured to shunt a current to ground while a second DCvoltage derived from the first DC voltage remains above a predeterminedvoltage level.
 7. The electronic circuit breaker of claim 1, wherein themonitoring circuit is fabricated as an integrated circuit.
 8. Theelectronic circuit breaker of claim 1, wherein the detection circuit isconfigured to detect a fault condition comprising at least one of aground fault, an arc fault, an over current condition, and a shortcircuit condition.
 9. The electronic circuit breaker of claim 1 whereinan application specific integrated circuit comprises the detectioncircuit, the detection circuit comprising a DC voltage or shuntregulator.
 10. A method of assembling an electronic circuit breakerconfigured to monitor and respond to a power supply and/or a detectioncircuit failure within the electronic circuit breaker, the methodcomprising: electrically coupling a trip switch between a sourceterminal and a load terminal, the trip switch configured to open andclose a current path in a power conductor between the source terminaland the load terminal; electrically coupling an input of a power supplyto the power conductor, the power supply configured to convert an ACvoltage into a first DC voltage and comprising a first DC voltageoutput; electrically coupling a detection circuit to the first DCvoltage output, the detection circuit comprising a second DC voltageoutput; and electrically coupling a monitoring circuit to the powersupply input and to the second DC voltage output, wherein the monitoringcircuit is configured to respond to a power supply or detection circuitfailure by causing the trip switch to open the current path between thesource terminal and the load terminal.
 11. The method of claim 10further comprising electrically coupling the monitoring circuit to acontrol circuit configured to control the opening and closing of thetrip switch.
 12. The method of claim 10 further comprising electricallycoupling a control circuit to the trip switch, the detection circuit,and the monitoring circuit, wherein the control circuit is configured tocontrol the opening and closing of the trip switch.
 13. The method ofclaim 12 wherein the control circuit comprises an SCR(silicon-controlled rectifier) or a TRIAC.
 14. The method of claim 10wherein the monitoring circuit is configured to monitor a DC voltageprovided at the second DC voltage output of the detection circuit and torespond to a drop in the DC voltage below a predetermined voltage levelby causing the trip switch to open the current path between the sourceterminal and the load terminal.
 15. The method of claim 10, wherein theelectrically coupling a monitoring circuit comprises: electricallycoupling a first pin of the monitoring circuit to the power supplyinput; electrically coupling a second pin of the monitoring circuit tothe second DC voltage output of the detection circuit; and electricallycoupling a third pin of the monitoring circuit to a control circuitconfigured to control the opening and closing of the trip switch.
 16. Amethod of detecting and responding to a power supply and/or a detectioncircuit failure within an electronic circuit breaker, the methodcomprising: monitoring a DC voltage within the electronic circuitbreaker; and responding to a drop in the DC voltage below apredetermined voltage level by causing a trip switch to open a currentpath between a source terminal and a load terminal of the electroniccircuit breaker.
 17. The method of claim 16 further comprising shuntinga current to ground while the DC voltage remains above the predeterminedvoltage level.
 18. The method of claim 16 wherein the monitoring a DCvoltage comprises monitoring a DC voltage provided at an output of adetection circuit within the electronic circuit breaker.
 19. The methodof claim 16 wherein the responding to a drop in the DC voltagecomprises: turning off a transistor electrically coupled to receive theDC voltage; diverting a current to a control circuit; energizing a tripsolenoid or electromagnet; and opening the trip switch to open thecurrent path between the source terminal and the load terminal of theelectronic circuit breaker.
 20. The method of claim 19 wherein thediverting a current to a control circuit comprises diverting the currentto an SCR (silicon-controlled rectifier) or a TRIAC to turn on the SCRor TRIAC.